Equipment for the dual application of granular and/or liquid lawn treatment materials has been described heretofore in the patent literature. U.S. Pat. No. 4,185,782, for instance, provides a dual purpose spreader which can dispense granular or liquid materials but not simultaneously. The spreader employs an impeller driven by the wheels and a container for the liquid material which is dispensed directly onto the impeller.
U.S. Pat. No. 4,281,780 also provides a spreader that can dispense granular or liquid materials, but not simultaneously. A liquid reservoir canister equipped with a pump is provided in the carrier. The liquid is pumped to a nozzle assembly and is distributed downwardly from the top of the hopper.
U.S. Pat. No. 4,352,463 provides a lawn treatment spreader for the simultaneous application of granular and dry materials; however, the liquid material is supplied from a tank carried by a truck, rather than by the spreader apparatus.
U.S. Pat. No. 4,483,486 provides a hand-operated apparatus for applying granular and liquid materials to lawns, both to enhance growth as well as control weeds and insects. The apparatus provides a storage compartment which includes granular storage bins and a space for a removable container for liquids. The granular material is dropped first onto a rotatable belt which is driven by the wheels and then onto a motor-driven spinner plate. The liquid material is spread by a pump which is mounted on the axle and driven by the wheels. In operation, the liquid can be fed to the outlet hose and to the nozzle, or it can be recirculated back into the reservoir by the activation of a solenoid.
Finally, U.S. Pat. No. 4,798,325 provides an apparatus and method for applying liquid and dry materials to lawns. The apparatus includes a hopper for holding the dry fertilizer materials and an impeller which is disposed beneath the hopper and rotatably driven by the wheels. The liquid treatment materials are stored in a tank which is U-shaped and fits around the front and sides of the hopper. An electric pump and motor, for pressurization of the tank are carried beneath the hopper and are powered by batteries. Nozzles are provided on a horizontal mounting bar forward of the wheels and impeller to discharge the material beneath the dry materials. Three solenoid valves are also provided for controlling the flow of fluid to the nozzles. The patent discloses that for precise trim applications, the left and right nozzles can be turned to an off position and application continued through the center nozzle.
Thus, despite the relatively recent interest in dual purpose applicators for lawn and related turf areas, an applicator has not been provided heretofore which provides a very low volume of airborne spray material to minimize drift and which provides uniform application regardless of terrain.